The "veil of ignorance" is a thought experiment introduced by American philosopher John Rawls in his 1971 book, "A Theory of Justice." The concept is a method of determining the morality of a particular issue (e.g., wealth distribution, affirmative action) based on the following thought experiment: Suppose you were placed behind a veil of ignorance that wiped out all your knowledge about your personal characteristics and social and historical facts. You don't know anything about your gender, race, nationality, individual tastes, or personal identity. You cannot learn about the specific society you live in, its political or economic system, or its level of technological sophistication.
In such a condition, what principles would you choose to regulate the distribution of rights, duties, and material goods in your society when the veil is lifted? The concept posits that people will make decisions that ensure they will be secure or content, regardless of their social or economic status, once the veil is lifted. That's because, under the cover of ignorance, you have no idea what your position in society will be.
Rawls argued that the veil of ignorance would lead people to adopt two primary principles of justice: the liberty principle, which guarantees an equal set of fundamental liberties for each citizen, and the difference principle, which suggests that social and economic inequalities are only just if they result in compensating benefits for everyone, particularly for the least advantaged members of society. The concept is influential in philosophy, politics, economics, and beyond. It is often used as a tool for thinking about social justice, fairness, and equality.